The primary objective of this observational study is to measure the effect of use of combined oral contraceptive (COC) or depo-medroxyprogesterone acetate (DMPA) on the acquisition of HIV infection. The study will compare rates of infection among women using COCs or DMP with rate of infection among otherwise similar women who do not use hormonal contraception. The secondary objectives of the study are: 1) to determine if the rate of HIV infection in hormone contraception (HC) users compared with non-users is modified by the presence or duration of other sexually transmitted diseases (STDs), and to measure whether the type of hormonal contraception (COC versus DMP A) has a differential impact on the rate of STD acquisition among women;and, 2) to examine contraceptive hormones and their effect on other factors which have been shown to influence HIV transmission (e.g., bacterial vaginosis, genital shedding, human papiloma virus (HPV), herpes simplex virus (HSV-2). The tertiary objective is to acquire, preserve, store and ship serum, plasma and peripheral blood mononuclear cells for subsequent viral isolation and genetic/antigenic characterization in support of HIVNETs HIV-l vaccine development initiative.